Gravity and Seismic Investigations of the Santo Domingo Basin, Rio Grande Rift, New Mexico
Thursday, 18 December 2014
The SAGE (Summer of Applied Geophysical Experience) program collected new gravity, seismic, electromagnetic and down-hole temperature data in 2014 in the Santo Domingo Basin and adjacent areas of the Rio Grande Rift (RGR) area of northern New Mexico. The SAGE 2014 data collection was part of an integrated geophysical study of the area initiated in 2010 and adds data and interpretations to a W to E transect of the RGR. The transect includes previous SAGE seismic refraction and CMP reflection profiles recorded in 2010 and 2011, some industry seismic reflection data, and detailed gravity observations. Seismic data consisted of a 4.8 km NW to SE profile (120 three-component stations in four overlapping deployments, 20 m station spacing, using a Vibroseis source – 20 m spacing for reflection VPs; 800 m spacing for refraction VPs) along the Borrego Canyon road with both refraction and CMP reflection coverage. About 50,000 seismograms were recorded. The surface conditions (dry unconsolidated sediments) increased surface wave energy and limited the signal-to-noise level of reflection arrivals although some wide-angle reflections with two-way times as great as 1.8 s were visible. The refraction data were modeled with first arrival travel time methods and mainly helped identify the velocity and minimum thickness of the Tertiary Santa Fe group sedimentary rocks in the Santo Domingo Basin. Interpretation of the seismic and gravity data along the transect was aided by refraction velocities, the existence of a nearby regional seismic reflection profile from industry, and lithologies and well-logs from a deep well. Gravity modeling, with significant control on depths of interfaces and densities from the seismic and drill hole data, indicates that the Santo Domingo sedimentary basin has a total depth of about 6 km.